Piston Slap: Concluding commencements regarding Stop/Start technology?

Chuck writes:

I am wondering about the newer cars that turn off when they stop at a light. Is this bad for the car overall?

Sajeev answers:

I think the short answer to this question is a solid “not really.” And it’s 100 percent absolutely not a bad idea if you’re a short-term owner who moves on to a new car once the odometer breaks that magic 100,000-mile mark. And that mark doesn’t mean much these days, but I digress …

When it comes to the level of complicated engineering in vehicles these days, start/stop technology is pretty straightforward. Denso’s tandem solenoid starters are so much smoother, nearly imperceptible compared to older designs. Ever driven a 2007 Saturn Vue Greenline with the first-generation BAS (belted alternator starter)? Well I do, and BAS didn’t feel so great inside the cabin relative to what you see below.

Anyway, the point here is that technology has advanced over time. And refinements happened in the process. Unless you have this system in a manual transmission vehicle, you almost forget its there unless you look at your average fuel economy and wonder how today’s large, overweight, complicated trucks and SUVs get such tolerable fuel economy. It’s totally worth the mild abrasiveness of a modern tandem solenoid starter to go from 0 mpg in traffic to N/A in one’s fuel economy calculations.

But I haven’t answered the question: What appreciable damage will a start/stop system have on a vehicle? The engine is the biggest concern, except I haven’t seen a start/stop system coming to life until the engine is up to operating temperature. So when it does work, the engine wear with warm oil will be minimal, if non existent. And given the short duration of this action, I doubt enough oil drains down into the pan to cause any significant increase in engine wear upon startup. Maybe this is an issue for vehicles running well over 250,000 miles, but most will wind up crushed in the junkyard before that happens anyway.

So for me, I’d enjoy the fuel savings (especially right now) and instead be more concerned with the durability of modern cars with turbocharged and direct injected engines. Because some designs need significant maintenance after 7+ years of heat cycling. Replacement parts and even upgraded bits exist, but they sure ain’t free to buy and install.

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